A comparative analysis of the effects of five natural and two synthetic antioxidants on the stability of canola oil

Considering very low amount of SFA as compared to PUFA in canola oil, and the fact that most of its natural antioxidants such as tocofeols are lost during processing, this oil is severly exposed to oxidative rancidity. During this study, the effects of five natural antioxidants, namely grindox 596, tocopherol 50, rosemary extract, grindox 1021 and ascorbyl palmitate and two synthetic ones (propyl gallate and TBHQ) which are extensively used in Iran, were in vestigated on the stability of canola Oil, in order to substitute it for synthetic antioxidants. Thus in 2004,in iran Developping Oil Seeds Cultivation Company Firstly the optimum amount of each additive antioxidant was determined by rancimat and recorded as given below: grindox 596(1000 ppm), tocopherol 50 (400ppm), rosemary extract (400 ppm), grindox 1021 (600ppm), ascorbyl palmatate (400 ppm), propyl gallate (100 ppm) and TBHQ (100 ppm) secondly the optimum amount of each antioxidant was added to RBD canola oil with or without addition of beta _ carotene. the stability of all samples were measuring peroxide values during three months storage at different determined by conditions such as exposure to direct sun light, darkness, on the shelf (in direct light), and in the oven. Results obtained in this study showed that addition of beta _ caroten did not have any significant effect on increasing the stability of canola oil stored in the oven, darkness or exposed to UV. although, it improved stability of the oil stored on the shelf, significantly. on the other hand addition of beta -carotene to canola oil which was exposed to direct light act as a prooxidant.Ascorbyl palmitate had a significant effect on stability of canola oil stored in darkness as compared to other antioxidants. Grindox 1021 also showed a significant effect on stability of the oil exposed to direct light, which indicates that G 1021 (AP + tocopherol) has a more desirable effect on stability of canola oil and is able to trap the photo sensitizers much better than other antioxidants. in other cases, TBHQ and AP found to be the strongest antioxidants, respectively. there were no significant differences among other antioxidants